Resistor



Dec. s, 1936. H, A, WlLUAMS 2,063,357

RESISTO'R Fined May 23, 1935 lll l INVENTUR,

PatentedDea8,l936

PATENT ori-lcs v ansrsroa Hiram A. Williams, St. Marys, Pa., assigner to The Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania Application May z3. 193s, sei-m Nn. 23,013

' s claims. (ci. zar-s3) My invention relates to resistors of the nonadjustable type adapted for use in the radio art and more particularly relates to a shell or sheathing for the resistance element.

5 It is an object of my invention to construct a compact resistor in which the resistance element has a cap attached to each end thereof and the caps retain an insulating shell or shield for insulating both the end caps and the resistance l element. I

Another object of my invention is to construct an insulating shell for a resistor which cooper ates with the end caps'to lock itself upon the resistance element. l A further object of my invention is to construct a fixed resistor wherein the resistance element is securely positioned within a molded insulator having overhanging ends.

'A further object of my invention is to provide an improved device of the character described, that is easily and economically produced, and which is sturdy in construction.

A further object of my invention is to reduce the complexity of the parts which comprise an insulated resistor; thereby reducing the cost of Y manufacturing such devices as described.

With the above and related objects in view, my invention consists in the details of construction and combination of parts, as will be more fully understood from the following detailed description, when `read in conjunction with the accompanying drawing in which:-

Fig. 1 is a fragmentary longitudinal sectional view of a resistor and its insulating shell.

Fig. 2 is a fragmentary longitudinal sectional view of a modification of my invention comprising a resistor and its insulating shell.

Fig. 3 is another modification of my invention.

Fig. 4 is still another modification of my invention.

Fig. 5 is an end view of the modified shell only, which is illustrated in conjunction with the end caps and resistance element in Fig. 4.

Fig. 8 .is a sectional view taken on the line 6 6 of Fig. 5.

Referring now in detail to the drawing, I disclose in Fig. l a' cylindrical shaped resistance element, generally designated as A, comprised of a mixture of conducting and non-conducting mai terial, the ends of which may be coated, as dethis description refers to similarly constructed elements.

'I'he resistance element A has two electrical conducting caps, generally designated as B and C, aixed to each end thereof. Although two caps are disclosed, the details of construction of one cap only will be discussed. since the construcf' tion of each cap is identical and the description of one cap applies to the other cap. The cap B comprises a cup-shaped member having a cy- 10 lindrical flange member III and a base member I2. The base member has a central opening therein of substantially the same diameter as the diameter of a non-corrosive coated wire conductor I6, such as soft tin copper wire. 'I'he ma.- 15 terial adjacent the opening is conically formed, so that the cone-like surface I1 extends outwardly. The wire has an end I8 expanded to a conelike shape so that its diameter is greater than 20 the `diameter of the central opening in the base I2. The wire is positioned through the opening so that the conically expanded end I t interfits with the interior surface of the cone-like portion I1, and the end surface of Athe wire con- 25 tacts a portion of the resistance element.

The expanded end of the wire is coated withv ux prior to being placed through the cap, and after the wire I6 is in place,` a small piece of solder' I9 is placed on the cone-like end I8, heat 30 applied, as from -a spot welder, so the solder flows between the surface of the cone-like end I8 and the cone-like portion of the cap to effect a good, non-corroding electrical contact.

The wire conductor may be covered with insu- 35 lating material 26, such as rubber, and the free end of each wire conductor may be soldered, or held in its circuit by any other suitable means.

A shell or sheathing, ,generally designated as D', enveloping the resistance element A is com- 40 prised of an insulating material, such as a phenolic condensation product known' under the trade-mark bakelite, and the shell has an outer 4A, and the surface 3i extends a longitudinal distance nearly equal to the longitudinal distance between the ends 344, 35 of the caps B and C, 55

respectively. "Thus, to retain the shell in position the central circular surface 3i will have its radially extending edges 36, abut the ends 34, 35, respectively, or the caps B and C. Therefore, there is no need or employing other means to retain the insulating shell D in position.

The length oi the shell D, which is made longer than the overa-ll length of the resistance element plus the thickness of the walls of the end caps B and C, is another important consideration. The purpose of having the ends 30, 32 of the shell overhang the ends of the resistance element is to prevent electrical Contact of the resistance element and its caps with any other electrical conductors which would result in a short circuit.

The steps in the process of assembly o! the elements comprising the resistor illustrated in Fig. l are as follows:

The resistance element A is formed separately from the formation of the caps B and C and their respective conducting Wires. The wire i6 with its cone-shaped end i8 iiuxed is inserted into the opening in the cap, so that the complementary cone-shaped members interiit; a piece of solder is placed on the end of the Wire and heat applied by a spot welding machine so that the solder ows between the intertting cone-shaped members. The shell or sheath is, also, formed separately from the caps and the resistance element. With the various elements above described, one cap B, for example, is forced upon one end of the resistance element A by means cf a small hand press (not shown), then the shell or sheath D is slipped into position upon the resistance element, and subsequently the second cap C is pressed upon the other end of the resistance element by the hand press, thus completing the unit.

It is to be observed that the at end I8 of the conductor wire IS, most of the inner surface 20 of the base and the inner curved surface of the cylindrical member l B engages the resistance element A adjacent one of its ends.

In Fig. 2 I disclose a physical modification of my invention wherein a substantially moisture proof shell or sheathing, generally designated" as E, envelopes or encases the resistance element A and its end caps B and C.

The insulating shell E has its overlapping ends screw-threaded as at 4D, 4|. End closure caps, generally designated as 43, 44, of insulating material have screw threads thereon to cooperate with the complemental threads on the shell E.

An opening through each cap permits the'c0n' ductor wire to pass therethrough so that the resistance element Will be substantially unaffected by dust and dirt with the lead-of! wires completely insulated. The complete unit is made substantially moisture proof to reduce to a minimum the changes in the value oi' the resistance with changes of humidity in the air.

In Fig. 3 I disclose another modiilcation of my invention for encasing a resistance element in an insulating shell in order to prevent the resistance element from creating a short circuit by engaging some extraneous electrical conductor. and

wire, generally designated as G, is connected to the cap F by having an end 50 and a portion 52 close thereto swedged to the base oi the cap. A cylindrical insulating shell, generally designated as H, has a disc-like base 54. integrally formed with the cylindrical body member, and the shell partially encases the resistance element A and its respective caps B and F. l

In order to secure the shell H about the resistance element so that it will not jerk, or oscillate back and forth, because of the lack of locking features on its inner cylindrical surface or bore 56, as is illustrated in Figs. l, 2, and 4, the base 54 of the shell, by virtue of an opening therein, is slipped over the wire G, and then the wire, of dead soft tinned copper, has die clamps (not shown) tightened around it; the die clamps are placed adjacent the outer dat surface of the base 54 to raise a protruded portion 58 so that the base 54 will be fastened intermediate the expanded portions 52 and 58 of the wire. Thus, the resistance element will be encased by the shell H. 'I'he insulation illustrated as being over the wire may be dispensed with or utilized as is desired. An edge 55 of the cylindrical shell H overhangs the resistance element A to space the resistance element A and its cap B from other Hlive" conductors that are not to be electrically engaged.

Although the wire G, in Fig. 3, is illustrated as being held to the cap F by the expanded end and the expanded portion 52, this construction may be dispensed with and the wire soldered into position as has already been described. The shell E, however, is held from moving in one direction by the expanded portion 58.

In Figs. 4, 5, and 6 I illustrate another modification of my invention wherein a self-holding cylindrical insulating shell, generally designated as J, is of a length greater than the overall length oi' the resistance element plus the thickness of the walls of its end caps B and C. The shell J has a plurality of short segmental equi-spaced radially projecting portions 60, 6 I, 62 located to terminate intermediate the ends 34 and 35 of the caps B and C, respectively.

Each of the projecting portions 60, 6l or 52 are of a length approximately equal to the distance between the ends 34, 35 of the respective caps B and C on the resistance element A; and each portion extends inwardly from the main inner curved surface a distance approximately equal to the thickness of the cap metal. Each transverse edge o! each projecting portion'may engage a portion of the peripheral end o! each cap thereby retaining the shell in position.

Although three projecting portions are illustrated as being used, one or more projecting portions may be employed.

By the device illustrated in Fig. 4, it is seen that a less quantity of material is used for the sheathing.

Zt is to be understood that the conducting end caps, the shell or sheathing, and the lead conductors may be varied in shape without departing -from the spirit ot my invention.

Although my. invention has been described in ,considerable detail, such description is intended as illustrative rather than limiting, since the invention may be variously embodied, and the scope oi' the invention is to be determined as claimed.

I claim as my invention:-

l. A lxed resistor comprising a. resistance eleindividual wire conductor suitably connected thereto, an insulating sheath of cylindrical formation, an insulating base integrally formed with one end of said cylindrical sheathing, said base having an opening therein, a portion of one wire conductor within the base opening, and the interior surface of said base being located in immediate proximity to one cap vwhereby the cap prevents movement of the sheathing in one direction and the wire conductor adjacent the outer surface of said insulating base being expanded to prevent movement of the sheathing in the otherdirection.

2. A flxed resistor comprising a resistance element, a plurality of caps, each cap frictionally engaging one end of said resistance element, a plurality of wire conductors, each cap having an individual wire conductor suitably connected thereto, an insulating sheathing of cylindrical formation, an insulating base integrally formed with one end of said cylindrical sheathing, a portion of one wire conductor 4withinsaid opening, the interior of said base being located in immediate proximity to one of the resistance element caps to prevent movement of the sheathing in one direction, and the wire conductor adjacent the outer surface of said insulating base being expanded to prevent movement of the sheathing in the other direction, and the other end of said sheathing being open and or a length to overlap the end of the resistance element.

3. As a new article of manufacture, a fixed resistance element, an electrical conducting cap comprising a hollow cylindrical member and having a flange which substantially closes one end of said cylindrical member, said cap being adapted to be flrmly attached to one end of said resistance element, a, hollow cylindrical insulating member overlapping the resistance element and the cap,

said insulating member having a substantially closed base, said base having an opening therein, a wire having one end expanded so that it engages a portion of the conducting cap on the inner side of the conducting cap flange, and another portion of the wire being expanded to engage an outerl portion of the conducting cap flange, and the wire being expanded so that it engages a portion of the insulating base on its outside surface whereby the conducting cap and the insulating member will be securely held together.

4. A fixed resistor comprising a resistance element, a plurality of caps, each cap frictionally engaging one end of .said resistance element, a'

plurality of ywire conductors, each cap having an individual wire conductorl suitably connected thereto, an insulating sheath of cylindrical formation, an insulating base integrally formed with one end of said cylindrical sheathing, said base having an opening therein, a portion of one wire conductor within the base opening, the interior surface of said base being located in immediate proximity to one cap whereby the cap prevents movement of the sheathing in one direction and the wire conductor adjacent the outer surface of said insulating base being expanded to prevent movement of the sheathing in the other direction, the cap engaging the resistance element adjacent the open end of said insulating sheath comprising a cylindrical conducting member, an electrical conducting flange 'extending from the peripheral edge of one end of said cylindrical member, the center of said flange being shaped as a frustrum of a cone, an opening at the narrower portion of said frustrocone, and a conductor having an end shaped as a frustrum of said cone and being adapted to interflt with the frustro-cone portion of the flange.

5. A flxed resistor comprising a resistance element, a plurality of caps, each cap frictionally engaging one end of Asaid resistance element, a plurality of wire conductors, each cap having an individual wire conductor suitably connected thereto, an insulating sheath of cylindrical formation, an insulating base integrally formed with one end of said cylindrical sheathing, said base having an opening therein, a portion of one Wire conductor Within the base opening, the interior surface of said base being located in immediate proximity to one cap whereby the cap prevents movement of the sheathing in one direction and the wire conductor adjacent the outer surface of said insulating base being expanded to prevent movement of the sheathing in the other direction, an electrical conducting ange extending from the peripheral edge of one end of said cylindrical member, the center of said flange being shaped as a frustrum of a cone. an opening at the narrower portion of said irusto-cone, and a conductor having an end shaped as a frustrum of cone and being adapted to interflt with the frustro-cone portion of the flange, and solder between said frustro-cone members for firmly uniting said members together.

HIRAMaWnmAMs. 

